Hi all, I hope this topic was already floated in the Si-list. I would like to get clear idea about this, so please give your reply over the following queries. I have seen and even I use to provide void over the power planes under differential signal of Ethernet signal after isolation transformer. My understanding is to provide void in the power planes, is to avoid noise (or voltage surge ) couple between the digital planes in the PCB and cable entering in the front panel of the board. But I had seen people's providing void in the following manner: 1. Void under the Ethernet signals and E1 signals in the secondary side of the isolation transformer. 2. Some will not provide void under these signals. They will route over the ground plane. 3. Some will provide void just below the isolation transformer, but not under the differential signals. In this which methodology is true? Which one have to be followed in the network application? And what is the reason behind the void under these signals? If anybody will suggest app notes and reasons, that will be great for my understanding. Thanks & Regards, Arun Kumar ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List technical documents are available at: http://www.si-list.net List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu